We are approaching the 40th anniversary of the political campaign which transformed the Democratic party — the presidential candidacy of Eugene McCarthy.

By the fall of 1967, the first important electoral campaign of what was then being called the New Left was getting underway in New Hampshire, culminating in the strong McCarthy showing that forced President Johnson from the White House.

The McCarthy campaign was not only extraordinary by historical standards — imagine a Republican opposing Lincoln during the Civil War or a Democrat opposing Roosevelt in 1944 — but marked the entrance into national politics of the new class of Democrats who would come to dominate the party; both Hillary Clinton and a member of her inner circle, Harold Ickes, cut their political teeth in the McCarthy campaign, as did John Podesta, another long-time confidante to the Clintons. They were among the Ivy League-educated liberals drawn to politics as a means to express moral sentiments — or what Mrs. Clinton, a McCarthy volunteer herself would later call a “politics of meaning.”

With Mrs. Clinton now the odds-on favorite to win the Democratic presidential nomination, it’s worth reflecting on that formative political experience — and the extent to which it may still influence her campaign approach.

In addition to its “bring the troops home now” message, the McCarthy campaign also introduced new tactics into campaigning, ranging from its reliance on a core group of ideologically-motivated funders — presaging George Soros — door-to-door canvassers brought in from out of town, and, perhaps most memorably, a tactic which its young volunteers adopted known as “Clean for Gene.” Viewed most simply, it involved long haired New Left types getting haircuts, before hitting the streets of Concord and Manchester.

In his definitive 1970 memoir of that campaign, “Nobody Knows,” McCarthy speechwriter Jeremy Larner described the tactic this way: “There was to be said here for the self-imposed discipline of the youth corps. ‘Clean for Gene’ was a policy of practical political sophistication. For several years, the peace movement had been having a mixed effect on America. In New Hampshire it was possible for students to work effectively against the war and the assumptions behind the war without an exchange of hostility.”

In other words, “Clean for Gene” was about much more than a haircut. It was a tactic designed to package one’s beliefs behind a misleading façade — to present oneself as the kid next door, an All-American boy or girl. In other words, this was a tactic meant not so much to disarm as to deceive. Notably, it established a pattern. Time and again, left-leaning organizations have, in the years since, sought to wrap themselves in an outer mantle of traditional Americanism, despite their distaste for it. Think of “People for the American Way” and its founding president, Anthony Podesta, whose younger brother John was the founding president of Center for American Progress. Or think of the abortive left-leaning radio talk show network, Air America, or the 2004 Kerry campaign bumper sticker, “Support America, Defeat Bush.” All stem from the “Clean for Gene” tactic — asserting one’s tie to American traditionalism no matter one’s actual politics.

One can go further and wonder, indeed, whether Mrs. Clinton’s nominally difficult to understand record — voting initially for the war in Iraq, offering apparently centrist views on everything from abortion to flag-burning to statements about the importance to her of “faith” — are themselves a long-playing version of “Clean for Gene.”

Indeed, this would be the central question of a Hillary Clinton presidency: have her views evolved or, is she simply saying and doing what seems necessary to enable her to bring a social democratic agenda to power?

This may well be what those who dislike Mrs. Clinton sense about her — a merely tactical and transitory embrace of views that are the equivalent of dressing conservatively or getting a haircut for the McCarthy campaign.

The possibility that her core beliefs have changed can’t be dismissed. But neither can the possibility that she still might use tactic from 40 years ago and still could be “Clean for Gene.”

Mr. Husock is a contributing editor of City Journal.